Kaiji Itou is a good-for-nothing loiterer who spends his days drinking beer and stealing hubcaps—that is, until he ends up being tricked by his former co-worker. Unable to suddenly repay his friend's huge debt all by himself, Kaiji is offered a shady deal to participate in an illegal underground gamble on a cruise ship. This turns out to be nothing more than the beginning of his new life of hell—thrown headlong into a life-threatening roller coaster of mind games, cheating, and deceit.

Hiromichi Kojima, the star batter of the Lycaons, heads to the southern Japanese island of Okinawa to train and find a new pitcher for the team. There, he meets Toa Tokuchi, a 134-kmph pitcher and the undisputed king of a gambling form of baseball called "One Outs". At Kojima's urging, Tokuchi signs up with the Lycaons under an unusual contract: he gets 5,000,000 yen for every out he pitches, but loses 50,000,000 yen for every point he gives up. A high-level psychological game of baseball, gambling and logic is about to begin..